Problem: Compute $\frac{x^6-16x^3+64}{x^3-8}$ when $x=6$.
Explanation: Note that $\left(x^3-8\right)^2=x^6-16x^3+64$. So $\frac{x^6-16x^3+64}{x^3-8}=\frac{\left(x^3-8\right)^2}{x^3-8}=x^3-8$. So, the answer is $6^3-8=216-8=\boxed{208}$.